Temperature measuring apparatus for heating roller

ABSTRACT

A quartz crystal resonator is embedded in a circumferential wall portion of a heating roller. The heating roller is provided with a rotary electrode, while a stationary electrode is mounted to a stationary portion of the apparatus to form a rotary air capacitor in cooperation with the rotary electrode. The quartz crystal resonator has two terminals, one of which is grounded and the other of which is connected to an oscillation circuit through the air capacitor variation of impedance of the detector to the outside of the heating roller without any mechanical contact with the latter.

[451 Sept. 11,1973

TEMPERATURE MEASURING APPARATUS FOR HEATING ROLLER Inventors: SigeruOtani; Fuminori Honda, both of Mihara; Kiyoto Mitani, Fukuyama, all ofJapan Teijin Limited, Osaka-shi, Osaka, Japan Filed: July 6, 1972 Appl.No.2 269,463

Assignee:

Foreign Application Priority Data Oct. 6, l97l Japan..... 46/09l896(utility model) u.s. c1 219/1049, 2l9/10.61, 219/1075,

, p t 219/471 1111.01. H05b 5 00 Field 6: Search 219/1049, 10.75,219/1077, 10.61, 469, 471, 504; 73/351, 362 AR, 339 A References CitedUNITED STATES PATENTS 2 1967 'Matsuura et al 73 351 3 -taU lO 1,1 l6 l3,7 v

3,463,893 8/l969 Chitu 2l9/l0.75 X

Primary Examiner-J. V. Truhe Assistant ExaminerB. A. ReynoldsAttorney-E. F. Wenderoth et a].

57 ABSTRACT A quartz crystal resonator is embedded in a circumferentialwall portion of a heating roller. The heating roller is provided with arotary electrode, while a stationary electrode is mounted to astationary portion of the apparatus to form a rotary air capacitor incooperation with the rotary electrode. The quartz crystal resonator hastwo terminals, one of which is grounded and the other of which isconnected to an oscillation circuit through the air capacitor variationof impedance of the detector to the outside of the heating rollerwithout any mechanical contact with the latter.

, 9 2 Claims, 5 Drawing Figures PATENIEDSEPI I ma SHEEI 1 0F 2 FlG.-1

FIG.5

TEMPERATURE MEASURING APPARATUS FOR HEATING ROLLER This inventionrelates to a temperature measuring apparatus for a rotatable heatingroller used for heating treatments of synthetic fibers.

Many thermo-plastic synthetic fibers, such as polyester and polyamide,are usually heat-treated, for example drawn, while they are wound on ametalic heated rotary body. The temperature of the surface of the rotarybody should be maintained exactly at a predetermined value. For thatpurpose, it has been proposed to correctly detect the temperature of therotary body as electric signals which are taken out of the rotary bodyand supplied to a controller. As the most preferable temperaturedetectors, a thermistor or thermocouple are employed, which are embeddedin a circumferential wall portion of the rotary body to detectelectrically the temperature most similar to the exact temperature ofthe surface of the rotary body. The detected signals have been generallytaken out of the rotary body by use of a slip ring. In such apparatus,however, the electric signals taken out are not always constant becauseof the fluctuation of electric impedance due to contact resistance whichis caused by wearing of the slip ring and the contact point where abrush is in contact with the slip ring, and also by deposition of dustthereon. Thus, there sometimes occurs a critical error and a noisesignal, which make it impossible to effect an accurate temperaturecontrol.

The disadvantages described above have suggested several electricalcoupling means which facilitate to take the electrical signals out ofthe rotary body (without any mechanical contact therewith. Typical andwell known electrical coupling means of dielectric couplings bytransformers and electrostatic couplings by rotary capacitors.

In U.S. Pat. No. 3,463,893, it has been proposed to provide the abovementioned electric coupling means at a shaft of a heating roller, and,in U.S. Pat. No. 3,417,219, a dielectric coupling means is provided in aheating body of a heating roller. In the former arises a disadvantagethat the shaft must be made longer and a tunnel must be provided in theshaft to allow lead wires to be threaded therethrough, so that suchtemperature control apparatus is not suited for use with a drawingmachine having multiple spindles. The latter provides a dielectriccoupling means comprising two opposite cores each coiled by a lead wire.These two cores are provided in a stationary heating body and *a roller,respectively, concentrically with the driving shaft. Accordingly, thereis no disadvantage such as experienced in the apparatus of the formerU.S. Patent. However, when such dielectric heating method is applied,magnetic flux passes through the cores described above to disturb theelectrical signals. Therefore, additional means for preventing thedisturbance of electrical signals for temperature control are needed,and since the stationary core and the rotatable core constituting therotary transfonner should be accurately provided in the heating body andthe roller, respectively, the structure becomes complicated andmanufacturing cost and maintaining cost go higher. Moreover, the rotarytransformer cannot be made to be small because of neces saryheat-proofing, and it has a basic disadvantage rather than the rotaryair capacitor.

Nowadays numerous heating rollers are concentrically controlled by aplurality of switching system in which output signals of the detectorsinstalled in each temperature detecting circuit are required to be ofthe same value at the same temperature with one another. When a quartzcrystal resonator is used as temperature detector, the quartz crystalresonator is so smal that it can be embedded in a preferable position ofthe circumferential wall of the heating roller, and the quartz crystalresonator has an advantage that it may allow its oscillation frequencyto change almost linearly in accordance with a temperature variation.

Accordingly, an object of the present invention is to provide atemperature measuring apparatus simple in structure and easy to make andto maintain, wherein the temperature detector embedded in thecircumferential wall of the rotary body is associated with theelectrical circuits provided out of the rotary body by electrostaticcoupling mean without mechanical contact.

According to the present invention, a temperature measuring apparatus isprovided comprising a cupshaped heating rotary body having a quartzcrystal resonator embedded in a circumferencial wall portion thereof,and a rotary air capacitor having a rotary electrode and a stationaryelectrode, one of two terminals of said resonator being connected withthe rotary body which is grounded and the other terminal being connectedwith the rotary electrode provided at an open end wall portion of theheating rotary body through an electrical insulating material, saidstationary electrode being mounted through an electrical insulatingmaterial to a stationary portion of the apparatus in such a manner thatsaid stationary electrode is opposite to said rotary electrode with anair gap therebetween. The quartz crystal resonator is connected to acircuitthrough the rotary air capacitor to form an oscillation circuitwhich is grounded. By the apparatus described above, the temperature ofthe heating rotary body is detected as the ferquency of the oscillationcircuit. The word ground used herein means to form a short circuit byelectrically connecting to a frame of theapparatus.

The two electrodes may be disk like shapes attached to a flange end of astationary frame which supports the cup-like rotary body and to rearwardend surface of the rotary body, respectively. The two electrodes alsomay be cylindrical shapes attached to an outer circumferential surfaceof the flange and an inner circumferential surface of the rotary body,respectively, or attached to a cylindrical inner circumferential surfaceof the flange and an outer circumferential surface of the rotary body.Insulating materials for the electrodes can preferably be fixedintegrally to the circumferential wall portion of the rotary body andthe stationary flange portion where the electrodes are attached.However, these insulating materials may be removably mounted thereto.

Both electrodes have relatively large opposing areas, so that the rotaryair capacitor of the present invention can have a relatively largeelectrostatic capacity. This means that the rotary air capacitor has arelatively low impedance for the frequency of the oscillation circuit.Therefore, even if there is some fluctuation of the space between theelectrodes of the rotary air capacitor, the variance of the capacity ofthe rotary air capacitor due to such fluctuation will hardly affect theferquency of the oscillation circuit determined by the naturaloscillation of the quartz crystal resonator which is responsive totemperature.

In the present invention, the rotary electrode of the rotary aircapacitor is attached to the open end portion of the rotary body, sothat the quartz crystal resonator is connected to the rotary electrodeby a lead wire extending along the circumferential wall of the rotarybody. Such structure of the present invention does not require any axialbore in the driving shaft through which the lead wire of theconventional apparatus has passed.

Thus, the apparatus of the present invention will be cheaper tomanufacture and easier to maintain. Furthermore, there is no fear thatthe lead wire will be cut or moved out of place when the rotary body isremoved from the driving shaft.

The oscillation frequency F, may be used directly or indirectly, afterconverting to pulses or voltage signals, to indicate the temperature ofthe heating roller or to control the temperature thereof. In order toconvert the oscillation frequency F, to a lower frequency, preferably,another oscillation circuit of the same kind as the above describedoscillation circuit is provided, and the signals of the two oscillationcircuits are induced to a mixing circuit to take out the frequency ofdifference between the oscillation frequencies.

The aforementioned and other objects and features of the presentinvention will become apparent from the description of specificembodiments thereof, when read in conjunction with the accompanyingdrawings in which:

FIG. 1 is a sectional view showing a principal portion of a temperaturecontrol apparatus for a heating roller according to the presentinvention.

FIG. 2 to FIG. 4 are sectional views showing temperature detecting meansfor the heating roller according to the present invention, and

FIG. 5 is a circuit diagram showing an external electric oscillationcircuit of the present invention.

In a first embodiment of the present invention shown in FIG. 1,reference numeral designates a cup-like heating roller having a hollowrecess opening at one side to receive a stationary iron core therein.The heating roller 10 also has a narrow recess 12 in its circumferentialwall portion 11, in which a quartz crystal resonator X-tal 1 is snuglycontained. A driving shaft 14 of the roller 10 is rotatably supported bya stationary frame portion (not shown) to rotate by a suitable drivingmeans. Induction heating coil 13 is mounted to a stationary iron core 15with an air gap 16 from the inner circumferencial wall portion of thecup-like roller 10. The induction heating coil 13 is connected with apower source by conductive wire 19 through Triode AC Switch 17 operatedby a controller. Electrical insulating rings 20 and 21 made of 10mmthick steatite are provided at a rear end surface of the roller 10 and aflange end surface of the iron core 15 to oppose each other with a spaceof 1.0mm therebetween. These insulating rings are provided withelectrodes 22 and 23 of silver of 10p. thickness formed by silverbaking.

Of two lead wires 24 and 25 of the quartz crystal resonator X-tal l, thelead wire 24 is connected with the electrode 22 which is rotatedtogether with the roller 10 but insulated therefrom and the other leadwire 25 is electrically connected with the roller 10 which is groundedthrough the shaft 14 and bearings (not shown). Numeral 26 shows that theroller is substantially grounded. The stationary electrode 23 isconnected with an external circuit 28 through the lead wire 21. Numeral29 shows that the oscillation circuit 28 is grounded through the frameof the apparatus, which means that the oscillation circuit 28 iselectrically connected with the lead wire 25 of the quartz crystalresonator X-tal 1.

According to the first embodiment of the present invention describedabove, the quartz crystal resonator X-tal l is connected to theoscillation circuit in the external circuit 28 through a rotary aircapacitor Cs without a mechanical contact. The output frequency from theoscillation circuit is led to a controller 18 by way of a lead wire 30to control the temperature of the roller 10.

In a second embodiment of the present invention shown in FIG. 2, anelectrically insulating ring 20 on which the electode 22 is attached isremovably mounted to the roller 10. Namely, screw threads are providedon the rear circumferential flange portion 31 of the roller 10, andclamping piece 33 such as a cap nut is engaged to the screw threads. Astepped portion 34 of the clamping piece 33 contacts at its innersurface with an outer stepped surface of the electrically insulatingring 20 through a packing 36 interposed therebetween, thus fixing thering 20 to the rear end surface of the roller 10.

In place of the flat ring-shaped electrodes 22 and 23 shown in the aboveembodiment, two cylindrical elec trodes arranged concentrically may beemployed.

In a third embodiment of the present invention shown in FIG. 3,cylindrical electrodes 22 and 23 are provided at the innercircumferential surface near the free open end of the roller 10 and theouter circumferential surface of the induction heating coil 13,respectively. In a fourth embodiment of the present invention shown inFIG. 4, the cylindrical electrodes are provided at the outercircumferential surface of the roller and the inner circumferentialsurface of the flange 15 of the stationary frame, respectively. Theseelectrodes 22 and 23 are formed by metal spraying on the electricallyinsulating meterials 20 and 21 which are also formed by ceramicspraying.

FIG. 5 shows, in detail, the external circuit disignated by referencenumeral 28 in the first embodiment of the present invention. Theexternal circuit comprises a temperature detecting frequency oscillationcircuit 37, a reference frequency oscillation circuit 38, and a mixingcircuit 39.

As described before, the lead wire 25 of the quartz crystal resonatorX-tal embedded in the rotary body is grounded, and the other lead wire24 is connected with the rotary electrode 22 which forms the rotary aircapacitor Cs in cooperation with the stationary electrode 23 connectedwith the feedback input side of the temperature detecting colpittsfrequency oscillation circuit 37. The oscillation frequency F, of thiscircuit 37 is determined by the natural oscillaiton of the quartzcrystal resonator X-tal 1. That is, the oscillation frequency F, variesin response to the temperature of the rotary body as sensed by X-tal 1.The output frequency F, and F, of the two oscillation circuits 37 and 38are led into the mixing circuit 39 to generate the deviation Fotherebetween, i.e. Fo F, F,. The output frequency Fo which correspondsto the temperature of the roller 10 is applied to the controller 18through the lead wire 3. The oscillation circuits 37 and 38 and themixing circuit 39 are known circuits except for the provision of therotary air capacitor Cs and equivalent capacitance Co for peripheralportions to which the rotary air capacitor is mounted, and except forthe series arrangement of a compensation coil L1 and a variablecondenser Cv to a reference quartz crystal resonator X-tal 2.Accordingly, detailed description of these circuits are omitted.

According to the arrangement in which the reference quartz crystalresonator X-tal 2 is connected, in series, with the compensation coil L1and the variable condenser Cv, the value of the output frequency F0 canbe easily adjusted by operating the variable condenser Cv. For example,using the quartz crystal resonators X-tal l and X-tal 2 both being about8Ml-lz at room temperature and connected to the compensation coil L1 ofabout 60 p, H, when the variable condenser Cv is varied from 4.2PF to37.8 P F, the output frequency F0 varies from 63.6](Hz to 24.9I-lz whilethe heated roller is at about 100 C.

Though the coil L1 and the variable condenser Cv are connected in serieswith the reference quartz crystal resonator X-tal 2, they may beconnected in series with the detecting quartz crystal resonator X-tal 1.Such connection will have the same effects as mentioned above. I 7

While the invention has been explained and described with the aid ofparticular embodiments thereof, it will be understood that the inventionis not limited thereby and that many retaining and utilizing the spiritthereof without departing essentially therefrom will occur to thoseskilled in the art in appling the invention to specific operatingenvironments and conditions. For example, in place of the heatinginduction coil 13 mounted to the iron core 15, acasting heater may befixed to the roller 10.-

What is claimed is:

1. In a rotary heating roller apparatus comprising a cup-like rotarybody, a driving shaft removably connected at an opened portion of saidrotary body and a stationary heating means disposed with an air gapbetween the inner circumferential surface of said rotary body and theouter circumferential surface of said heating means, an improvedtemperature measuring apparatus comprising a temperature detectorembedded in a circumferential wallportion of said rotary body, and anelectrostatic coupling means which electrically connects saidtemperature detector to an external circuit annular disc-like rotaryelectrode attached to an annular open end surface of said rotary bodywith an electrical insulating material therebetween, and an annulardisk-like stationary electrode attached to a stationary portion of saidroller apparatus with an electrical insulating material therebetween,said stationary electrode being positioned opposite said rotaryelectrode; said temperature detector being a quartz crystal resonatorhaving two terminals, one of said terminals being connected with saidrotary body which is grounded through said driving shaft, the otherterminal thereof being connected with said rotary electrode; and saidexternal circuit having an oscillation circuit which includes saidquartz crystal resonator, whereby the temperature of said rotary bodycan be detectd as the frequency of said oscillation circuit.

2. In a rotary heating roller apparatus comprising a cup-like rotarybody, a driving shaft removably connected at an opened portion of saidrotary body and a stationary heating means disposed with an air gapbetween the inner circumferential surface of said rotary body and theouter circumferential surface of said heating means, an improvedtemperature measuring apparatus comprising a temperature detectorembedded in a circumferential wall portion of said rotary body, and anelectrostatic coupling means which electrically connects saidtemperature detector to an external circuit without mechanical contact,said electrostatic coupling means comprising a rotary air capacitorcomprising a cylindrical rotary electrode attached to a circumferentialwall portion of said rotary body with an electrical insulating materialtherebetween, and a cylindrical stationary electrode attached to astationary portion of said roller apparatus with an electricalinsulating material therebetween, said stationary electrode beingpositioned opposite to said rotary electrode; said temperature detectorbeing a quartz crystal resonator having two terminals, one of saidterminals being connected with said rotary body which is groundedthrough said driving shaft, the other terminal thereof being connectedwith said rotary electrode; and said external circuit having anoscillation circuit which includes said quartz crystal resonator,whereby the temperature of said rotary body can be detected as thefrequency of said oscillation circuit.

1. In a rotary heating roller apparatus comprising a cup-like rotarybody, a driving shaft removably connected at an opened portion of saidrotary body and a stationary heating means disposed with an air gapbetween the inner circumferential surface of said rotary body and theouter circumferential surface of said heating means, an improvedtemperature measuring apparatus comprising a temperature detectorembedded in a circumferential wall portion of said rotary body, and anelectrostatic coupling means which electrically connects saidtemperature detector to an external circuit without mechanical contact,said electrostatic coupling means comprising a rotary air capacitorcomprising an annular disc-like rotary electrode attached to an annularopen end surface of said rotary body with an electrical insulatingmaterial therebetween, and an annular disk-like stationary electrodeattached to a stationary portion of said roller apparatus with anelectrical insulating material therebetween, said stationary electrodebeing positioned opposite said rotary electrode; said temperaturedetector being a quartz crystal resonator having two terminals, one ofsaid terminals being connected with said rotary body which is groundedthrough said driving shaft, the other terminal thereof being connectedwith said rotary electrode; and said external circuit having anoscillation circuit which includes said quartz crystal resonator,whereby the temperature of said rotary body can be detectd as thefrequency of said oscillation circuit.
 2. In a rotary heating rollerapparatus comprising a cup-like rotary body, a driving shaft removablyconnected at an opened portion of said rotary body and a stationaryheating means disposed with an air gap between the inner circumferentialsurface of said rotary body and the outer circumferential surface ofsaid heating means, an improved temperature measuring apparatuscomprising a temperature detector embedded in a circumferential wallportion of said rotary body, and an electrostatic coupling means whichelectrically connects said temperature detector to an external circuitwithout mechanical contact, said electrostatic coupling means comprisinga rotary air capacitor comprising a cylindrical rotary electrodeattached to a circumferential wall portion of said rotary body with anelectrical insulating material therebetween, and a cylindricalstationary electrode attached to a stationary portion of said rollerapparatus with an electrical insulating material therebetween, saidstationary electrode being positioned opposite to said rotary electrode;said temperature detector being a quartz crystal resonator having twoterminals, one of said terminals being connected with said rotary bodywhich is grounded through said driving shaft, the other terminal thereofbeing connected with said rotary electrode; and said external circuithaving an oscillation circuit which includes said quartz crystalresonator, whereby the temperature of said rotary body can be detectedas the frequency of said oscillation circuit.